Improvement in rifle-barrels



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lImprovement in Rifle-Barrels.

Patented Junev 1|, 1872` Im/enfer y UNITED STATES @PATENT FFICE.

MARVIN S. OOLVIN, OF EAST RANDOLPH, NEW YORK.

IMPROVEMENT IN RIFLE-BARRELS.

Specification forming part of Letters Patent No. l`27,8-19, dated June11, 1872.

To all whom it may concern:

Be it known that I, MARVIN S. GoLvIN, of East Randolph, in the county ofCattaraugus and in the State of New York, have invented certain new anduseful Improvements-in Rilie- Barrel; and do hereby declare that thefollowing is a full, clear, and exact description thereof', referencebeing had tothe accompanying drawing and to the letters of referencemarked thereon making a part of this specification.

Heretofore the bores of gun-barrels have been made polygonal, in whichcase the projectile to be used therewith had to be made of correspondingform; and the bores of barrels have been rilied -or provided withprojecting ribs, in which cases the projectile must be either forcedoutward to hll the grooves or must be cut by the inwardly-projectingribs and the patch of said projectile broken or cut through, and leadingof the barrel resulted; in other cases the bores have been made withaiiuted interior surface; but such have failed to give satisfactoryresults.

The object of my invention is to overcome the above difficulties; and tothis end my invention consists in providing a system of riiling having agenerally-dened polygonal form, but having what would otherwise be theapex of the angles rounded, and cut deeper on one side of said angle, soas to present a rounded series of channels and shoulders, whereby apatched projectile of a cylindrical or conical form, with a slight cupor depression in its butt, may be used without destroying the patch, andall of the advantages of the Whitworth or polygonal system of riiiin gderived without the necessity of a mathematical or mechanical tit forthe projectile.

In order to enable others skilled in the art to which myinventionappertains to make and use the same, I will now proceed to describe itsconstruction and operation, referring to the annexed drawing, in which-Figure l is a side view, part in longitudinal section, of myride-barrel. Fig. 2 is a crosssection of the same; and Fig. 3 is a sideview of the ball to be used in or with said barrel.

A represents the barrel, provided with a generally-deiinedpolygonal-twisted bore, having the channels a a., as shown. The twist inthis case is uniform, and, by preference, making one turn intwenty-three inches. The rounded grooves a a, being cut with one longand one short side, leave rounded and regular shoulders, and the form issuch that perfect and extremely-rapid rotation is given to acylindrical-patched projectile without cutting or breaking the patch,and, therefore, not liable to foul or lead. B represents a projectileVor ball slightly smaller than the bore, cylindrical, and having adepression or cup about onesixteenth of an inch deep at the buttthereof.

To adapt the projectile to my improved system of riiiing, the point orforward end is compressed or made of hard metal, while the rear end isleft or made of soft lead, so as to readily upset vupon the explosion ofthe charge, and thereby tightly fill the bore. The depression in thiscase is merely provided to hold the patch, which is of a good quality ofwritin g or bank-note pap er Wound twice around and twisted at the butt.

` Having thus fully described my invention what I claim as new, anddesire to secure by Letters Patent, is

rlhe improved system of riding, herein shown and described, consistingof a series of grooves or channels and corresponding rounded shoulderswith one short and one long side, both being curved, but the curve ofthe larger side having a radius considerably greater than that of thebore of the barrel, substantially as herein set forth.

In testimony that I claim the foregoing I have hereunto set my hand this10th day of January, 187

MARVIN S. COLVIN.

Witnesses 4 T. L. CAMP, UnARLEs H. HELMEs.

